Problem: Reduce to lowest terms: $- \dfrac{9}{7} \div \dfrac{1}{5} = {?}$
Answer: Dividing by a fraction is the same as multiplying by the reciprocal of the fraction. The reciprocal of $ \dfrac{1}{5}$ is $ \dfrac{5}{1}$ Therefore: $ - \dfrac{9}{7} \div \dfrac{1}{5} = - \dfrac{9}{7} \times \dfrac{5}{1} $ $ \phantom{- \dfrac{9}{7} \times \dfrac{5}{1}} = \dfrac{-9 \times 5}{7 \times 1} $ $ \phantom{- \dfrac{9}{7} \times \dfrac{5}{1}} = \dfrac{-45}{7} $